Download Focus on ecological complexity of aquatic systems

Focus on ecological complexity of aquatic systems: theory and application for a (ethic) sustainable management
A. Farina
Institute of Ecology and Environmental Biology, Environmental Science
Faculty, University of Urbino
Introduction
Water is one of the most important substances of our planet, distributed
from the high atmosphere to the Earth crust. Essential for the life of every
organism, water availability is becoming more and more strategic for the
future of the humanity.
Every branch of the natural sciences considers water as major agent of
land modeling, “habitat” for several forms of life, and finally essential
component of the cell cytoplasm. Large part of the evolutionary theory recognizes water as a relevant constraint factor and the release of organic
structure to water dependence, one of the most important evolutionary
trend.
Water per se is a chemical substance composed by two atoms of hydrogen and one atom of oxygen, no more no less. The simplicity of this molecule allows water to participate to several chemical, physical and biological processes. If life is cognition (sensu Maturana & Varela, 1980,
Maturana 1999), water is the substance that feeds cognition! From physic
to chemistry, from biology to geology and to ecology, water seems a
common subject investigated with different tools based often on distant
paradigms.
Springs, streams, rivers, lakes, lagoons and marshlands are considered
distinct entities common to every landscape. At a more accurate vision
these entities share water and potential energy associated, but also stock
of resources (minerals and nutrients) available for several systems that in
different way enter into contact.
Water is a substance manipulated mainly by solar energy and by biological processes. Its availability and state are under external constraints like
temperature, climate, and biological use. Water is a perfect example of
agent of complexity, appears in different states and takes part to several
abiotic and biotic processes.
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The aim of this contribution is to revisit the paradigm of the complexity (Lewin
1992, Cillier 1998, Manson 2001) under the perspective of the freshwater
dynamic and in the spirit to manage water resource in the best way for the
future.
Considering the universality of the water it is extremely hard to find a starting
point to face the complexity and breaking the circle of water processes. Under
the umbrella of the complexity paradigm, the risk to transform the phenomena observed into trivial facts, exists.
In order to explore the emergent properties of the freshwater systems, that so
important are for the ecosystem health (sensu Rapport et al. 1988) and for the
humanity, it is necessary to start with an ontological approach trying, if possible, to define such systems.
Some definitions
Water is the basis of our life, major component of the body of most of organisms; it appears in gas, solid and liquid state and at each change of state amazing amount of energy is mobilized.
Water is a substance of first importance for the thermic balance of our planet (Lovelock 1987) and one of the most important agent of land modification.
After the atmospheric gases, water is the most homogeneous substance that we
can find in a place.
Water participates to most of the physical, chemical and biological processes
and appears a very hard exercise to track back all the functions.
Water processes can be summarized according to a source-sink mechanism
(sensu Pulliam 1988) by which recharge areas (source) exchange water to discharge (sink) area. In a continuous process, water creates temporary structures
like springs (the site of emergence of subterranean water), lakes (temporary
deposit of surficial water), rivers (corridors that transfer water from higher
potential energy to lower potential energy areas), marshlands (impervious
sinks, often in proximity of sea costs), characterized by patterns that can be easily recognized. The physical constraints due to composition and soil structure
affect water circulation with recursive effects on soils. Erosion, river meandering, gravel deposition are some of the processes that can be associated to
water dynamics.
At a planet scale, water has invariant properties but scaling down and entering
into a more detailed world (by reducing the extension and increasing resolution
of the observed system) water, like any other substance, has an increasing spatial/temporal variance: water copes the land heterogeneity (sensu Kolasa &
Pickett 1991). Moving through scale we find at every resolution patterns asso2
ciated to water processes, and water dynamic creates a fractal-like structures
(Feder 1988). Stream, rivers, ponds, lakes, lagoon are the foot-print of water
presence.
Water regulates either biotic as well as abiotic processes changing diversity of
biological entities and type of chemical reactions.
Water states: order versus disorder
A water molecule can be in one of the three states (solid, liquid and gaseous),
can have a different energetic value, can be associated to many other chemical
substances, and can play different roles. The uncertainty of these conditions
obliges to use probabilistic models to predict place, condition and function of
a certain water mass.
When water is under the form of vapor, rain or snow, the patterns created by
these states have high variability and instability responsible of spectacular
process in the atmosphere. Water can drop from the atmosphere to the terrain
in very soft way (dew, fog) or in violent way (rain, hail, snow) according climate and local weather conditions.
The max probability that equals to the max disordered status is represented by
water vapor. Such disorder is reduced when water from vapor is transformed
in liquid (rain) and in solid one (ice). Moving from gas to ice water changes
recursively the energetic state incorporating new energy or dissipating the
existent energy according the phase in which is involved. Into a high-pressure
atmosphere (f.i. anticyclonic areas) water can have a very disordered status
(max probability) passing in short time (few minutes) in a very ordered system
(f.i. condensation of water vapor in cumulus-like clouds) with a very improbable status (high information, sensu Stonier (1998)). Rain distribution is often
very improbable in terms of geography and rain appears patchily distributed
across a region. When rain penetrates into the soil, water stochasticity increases dramatically, coping the permeability of soil, the capacity of organisms to use
water, the existence of underground “corridors” by which water moves into
direction of the minimum potential energy, etc. Soil ontogenesis is largely based
on the mechanical action of waters on the rocks and on chemical transformation
that water can provoke into soil compounds (weathering).
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Water “behavior”
Water has an unforeseeable behavior, also when “organized” in some invariant state (glaciers, lakes). Water
has not a goal function (Wilhelm &
Bruggemann 2000), neither a self-organization (Kauffman 1993) because is not
an entity, nevertheless its presence creates emergent processes with high level
of complexity. The major attribute of water is the capacity to link different substances and to dilute others. Definitively is the quantity and availability of water
associated to other physical or biological entities to create processes. The
quantity of water and the seasonal availability affects most of the land processes like plant grow, bacteria activity, insect outbreaks.
For every change in water content in the atmosphere as well in the ground, deep
changes occur either inside organisms then inside populations and communities.
Every concentration of water in the soil is copied by plants with specific individual adaptation. For instance in period of water abundance plants grow very
fast with larger leaves then in periods of water shortage. Contemporarily bacteria, fungi and nematoda living into the organic soil can increase in number
affecting the functionality of root systems of many plants. If water is very abundant, the gases in the soil are dramatically reduced and many aerobic organisms move or die away. When a drought period occurs, like summer 2003 in
the Mediterranean, soil metabolism is strongly reduced and the rarity of water
modifies texture of surficial soil layers with evident deep crevices.
Although changes in water availability occur with a very fast rhythm, many
organisms are able to cope such changes producing ephemeral processes like
quick flowering after a storm in desert climate, reproduction of amphibian in
temporary ponds after the winter rains, etc.
These are examples of complexity in which the mechanisms are not based
simply on cause-effect but on negative-positive feedback, on self-regulation, on
catalytic cycles and on stochasticity.
Water dynamics: a landscape perspective
Solar energy and gravity are the forces that mobilize water molecules and
change their states. Chemical energy is also released in different way during
the combination of water with other substances.
Ecosystem science investigates the flux of energy and nutrients across the systems (Odum 1983) and water is one of the most selected items.
According to a landscape perspective water processes can be considered in a
different way coupling water availability, distribution and function to the land4
scape units (Farina 2000).
Following this vision we could classify water processes on the basis of the land
units considered. For instance a woodland has water processes quite different
than mountain outcrops or cultivated lowland. For every patch, water
demand, content and quality change consequently. Generally water moves from
one patch to another along a gravitational gradient, but also according to the
capacity of patches to conserve water either in a physical way either through
the trophic chains of organisms. Longer a water mass remains in one patch
and more specific physical, chemical and biological characters create a distinct
“water footprint”.
At the border of each patch, environmental conditions change abruptly and a
special interface, the ecotone, regulates the exchange of energy, material, organisms as well as water (Gosz 1993, Risser 1995). Ecotones are created by natural processes and their presence is strongly constrained by human activity.
Ecotones are strategic structures in which waters lose particulates and solutes
after the strong characterization inside the patches, reducing the difference in
water quality from one patch to another. For instance a marshland located
between an irrigated field and a river functions as an ecotone, reducing the
concentration of dissolved N and P (Holland et al. 1991).
Man as modifier of water processes
From a human perspective water appears a primary substance for our life. We
need water for our metabolism, we need water to produce mechanical energy,
to use nuclear and fossil energy, to complete industrial processes, to produce
food, to clean objects and ourself. Different quantities, quality and different
states of water are requested for every utilization. Water is per se also a vehicle
for many chemical substances and chemical pollution of water can spread dangerous substances in areas far from the origin. Human development has created a web of artificial aqueducts that overlap and interfere with the natural surficial water pathways and aquifers.
Such activity influences water processes in different way and although all is
linked together distinct phases can be recognized.
Water is not destroyed by human activity but modified:
. changing the state (from liquid to vapor),
. the local availability (agriculture irrigation, industrial and domestic use),
. the chemical content (organic and industrial pollution).
Potential energy of water is also manipulated, creating dams, reservoirs and
spilling underground and fossil deposits.
Water availability is modified reducing natural reservoir and changing the
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geography of rivers and underground pathways.
Water use: sustainability versus ethics
In the title I have used the word sustainable to indicate the way to save and
maintain the ecosystem services (sensu Costanza et al. 1997) produced by
water. A reservoir in a mountain area could be considered a sustainable solution to water problems. A reservoir provide water in any season, can irrigate
field, can move the turbines of electric power plan, can supply the hotels during the tourist season.
But looking better I feel to refuse the paradigm of the sustainability as the
panacea of our problems. Sustainability is deeply rooted into an economic
vision of natural processes, and economic fundaments are far from a true ecological perspective.
I think that to face water problematics as well as other environmental challenges
it is necessary to change soon our vision of the life-supporting systems actually based on economic sustainability, and moving our argumentation into
ethics domain.
For instance, are far from ethics some conditions (related to water) that are
considered necessary or acceptable by our society, like:
. Cultivations that need humid climate and grown in dry climate by use of artificial irrigation,
. Mass tourism with high concentration along sea coasts and alpine regions and
consequent massive use of water,
. Use of pesticide and other dangerous molecules in agriculture and farm rearing,
. No limits to mixed use of drinking water for domestic and urban use,
. No limits to impervious surfaces cover.
Sustainability is an economic view of nature (sensu Costanza et al. 1997), we
need an ethics view of nature (Haber 2000). I am aware about the difficulties to
shift a paradigm but there is not a real progress without ethics. Ethics means the
control of our actions in order to do not harm people and other subjects and
to take into consideration also spiritual values. Today the debate is centered on
the convenience of our actions based on a pseudo ecological view of the world.
According to Farina et al. (2002), actually the planet resources are considered
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differently if the “Empty world ” or the “Full world” paradigm is adopted.
“Empty world” means that humanity recognizes the value of nature to be conserved but in remote and wild areas. Man is considered apart and not part of
nature. This vision contributes to separate humanity from the natural processes,
although the alibi of conservation sanctions to modify nature where people
develop. According to the “Full world” paradigm, people are part of nature and
the respect of natural processes are mixed to an “ethic” development. In other
words nature and man are elements of the same meta-domain (sensu Farina, in
prep.), and cultural landscape is the organized space.
Adopting this model means to understanding and incorporating in the human
activity the natural stochasticity of the events, the cyclic recurrence of favorable and unfavorable conditions, like the extreme weather conditions, learning
by feedback mechanisms the lesson granted by natural processes. In this way is
possible to reintegrated into the human development also the dynamic adaptation to the environmental phenomenology, lost during the last two centuries of
industrial revolution.
References
Cillier, P. 1998 - Complexity and postmodernism: Understanding complex systems. Routledge, New York.
Costanza, R., D’Arge, R., De Groot, R., Farbes, S., Grasso, M., Hannon, B.,
Limburg, K., Naeem, S., O’Neill, R.V., Paruelo, J., Raskin, R.G., Sutton, P., van
den Belt, M., 1997 - The value of the world’s ecosystem service and natural capital. Nature 387: 253-260.
Costanza, R., Cumberland, J., Daly, H., Goodland, R., Norgaard, R. 1997 - An
introduction to ecological economics. St. Lucie Press, Boca Raton, Florida.
Farina, A. 2000 - Landscape ecology in action. Kluwer Academic Publisher,
Dordrecht, The Netherlands.
Farina, A. (in prep.) - The landscape web. Toward a science of landscape.
Cambridge University Press, Cambridge.
Farina, A., Johnson, A.R., Turner, S.J., Belgrano, A. 2002 - “Full” world versus
“empty” world paradigm at the time of globalisation. Ecological Economics 45:
11-18.
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Feder, J. 1988 - Fractals. Plenum Press, New York.
Gosz, J.R. 1993 - Ecotone hierarchies. Ecological Applications 3: 369-376.
Haber, W. 2002 - Ethics and morality in the Sciences. INTECOL, Seoul (unpl.)
Holland, M.M., Risser, P.G., Naiman, R.J. 1991 - Ecotone. The role of landscape
boundaries in the management and restoration of changing environments.
Chapman & Hall, London.
Kauffmann, S.A. 1993 - The origins of the order: Self-organization and selection
in evolution. Oxford University Press, New York.
Kolasa, J. & Pickett, S.T.A. 1991 - Ecological heterogeneity. Springer-Verlag,
New York.
Lewin, R. 1992 - Complexity. Life at the edge of chaos. McMillan, New York.
Lovelock, J.E. 1987 - Gaia. A new look at life on earth. Oxford University Press,
Oxford.
Manson, S.M. 2001 - Simplifying complexity: A review of complexity theory.
Geoforum 32: 405-414.
Maturana, H.R. 1999 - The organization of the living: A theory of the living
organization. Int. J. Human-Computer Studies 51: 149-168.
Maturana,H.R. & Varela, J.F. 1980 - Autopoiesis and cognition. The realization
of the living. Rediel Publishing Company, Dordrecht, Holland.
Odum, H.T. 1983 - System ecology. John Wiley & Sons, New York.
Pulliam, R. 1988 - Sources-sinks, and population regulation. Am. Naturalist
132: 652-661.
Rapport, D., Costanza, R., Epstein, P.R., Gaudet, C., Levins, R. 1998 Ecosystem health. Blackwell Science, Oxford.
Risser, P.G. 1995 - The status of the science examining ecotones. BioScience
45:318-325.
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Stonier, T. 1998 - Information as a basic property of the universe. BioSystems
38: 135-140.
Wilhelm, T., Bruggemann, R. 2000 - Goal function for the development of natural systems. Ecological Modeling 132: 231-246.
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